Umbelliferone

Umbelliferone

Chemical structure of umbelliferone
Names
IUPAC name 7-Hydroxychromen-2-one
Other names 7-hydroxycoumarin, hydrangine, skimmetine, beta-umbelliferone
Identifiers
CAS Number	93-35-6 Y
ChEBI	CHEBI:27510 N
ChEMBL	ChEMBL51628 Y
ChemSpider	4444774 Y
Jmol 3D model	Interactive image
PubChem	5281426
InChI InChI=1S/C9H6O3/c10-7-3-1-6-2-4-9(11)12-8(6)5-7/h1-5,10H Y Key: ORHBXUUXSCNDEV-UHFFFAOYSA-N Y InChI=1/C9H6O3/c10-7-3-1-6-2-4-9(11)12-8(6)5-7/h1-5,10H Key: ORHBXUUXSCNDEV-UHFFFAOYAL
SMILES c1cc(cc2c1ccc(=O)o2)O
Properties
Chemical formula	C9H6O3
Molar mass	162.14 g/mol
Melting point	230 °C (446 °F; 503 K) (decomposes)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

File:UmbelliferoneSolid.JPG

Unbelliferone, or 7-hydroxycoumarin, is a yellowish white crystalline powder lacking the odor of coumarin, or any strong odor.

Umbelliferone, also known as 7-hydroxycoumarin, hydrangine, skimmetine, and beta-umbelliferone, is a widespread natural product of the coumarin family.

It absorbs ultraviolet light strongly at several wavelengths. Despite several indications that this chemical is photomutagenic, it is used in sunscreens. Umbelliferone has been reported to have antioxidant properties.

It is a yellowish-white crystalline solid that has a slight solubility in hot water, but high solubility in ethanol.

Natural occurrences and name

Umbelliferone's name is from the umbelliferae family of plants, and the plant family in turn was named for their umbrella-shaped inflorescences, each called an umbel.

Umbelliferone occurs in many familiar plants from the Apiaceae (Umbelliferae) family such as carrot, coriander and garden angelica, as well as in plants from other families, such as the mouse-ear hawkweed (Hieracium pilosella, Asteraceae) or the bigleaf hydrangea (Hydrangea macrophylla, Hydrangeaceae, under the name hydrangine).

It is one of the components of asafoetida, the dried latex from the giant fennel (Ferula communis).

It is also found in Justicia pectoralis (Acanthaceae).

Biosynthesis

Umbelliferone is a phenylpropanoid and as such is synthesized from L-phenylalanine, which in turn is produced via the shikimate pathway. Phenylalanine is lysated into cinnamic acid, followed by hydroxylation by cinnamate 4-hydroxylase to yield 4-coumaric acid. The 4-coumaric acid is again hydroxylated by cinnamate/coumarate 2-hydroxylase to yield 2,4-dihydroxy-cinnamic acid (umbellic acid) followed by a bond rotation of the unsaturated bond adjacent to the carboxylic acid group. Finally an intramolecular attack from the hydroxyl group of C2' to the carboxylic acid group closes the ring and forms the lactone umbelliferone.

 $\xrightarrow{PAL}$  $\xrightarrow{C4H}$  $\xrightarrow{C2H}$ 2,4-Dihydroxycinnamic acid $\longrightarrow$ Umbelliferone

Chemical synthesis

Umbelliferone is traditionally synthesized using the Pechmann condensation, from resorcinol and formylacetic acid (generated from malic acid in situ).

The Pechmann condensation as applied to umbelliferone

A newer synthesis uses methyl propionate and a palladium catalyst.

Ultraviolet fluorescence

Umbelliferone absorbs strongly at 300, 305 and 325 nm, with log ε values of 3.9, 3.95 and 4.15 respectively, and it fluoresces blue in both ultraviolet and visible light. The powerful absorption at three different wavelengths, coupled with the fact that the energy is dissipated safely as visible light, make umbelliferone a useful sunscreen agent. The absorption changes in alkaline solution, since the phenolic hydroxyl group is deprotonated (pK_a = 7.7).

Uses

The ultraviolet activity of umbelliferone led to its use as a sunscreen agent, and an optical brightener for textiles. It has also been used as a gain medium for dye lasers. Umbelliferone can be used as a fluorescence indicator for metal ions such as copper and calcium. It acts as a pH indicator in the range 6.5-8.9

Derivatives of umbelliferone

Umbelliferone is the parent compound for a large number of natural products. Herniarin (7-O-methylumbelliferone or 7-methoxycoumarin) occurs in the leaves of water hemp (Eupatorium ayapana) and rupturewort (Herniaria). O-Glycosylated derivatives such as skimmin (7-O-β-D-glucopyranosylumbelliferone) occur naturally and are used for the fluorimetric determination of glycoside hydrolase enzymes. Isoprenylated derivatives are also widespread, such as marmin (found in grapefruit skin and in the bark of the Bael tree) and furocoumarins such as marmesin, angelicin, and psoralen.

File:Umbelliferone derivatives.png

Herniarin and marmin, umbelliferone derivatives

Umbelliferone 7-apiosylglucoside can be isolated from the root of Gmelina arborea.

See also

• Aesculetin
• Laser dyes

External links

• USDA ARS info on uses